Internal combustion engines rely upon an ample source of clean air for proper combustion of a supplied fuel. Typically, an air intake system is provided for the engine and is connected with the intake manifold of the engine. Generally, an air intake system includes an air induction opening for drawing-in air and has a filter positioned such that the drawn-in air must pass through the filter to be cleaned prior to entering the intake manifold of the engine.
A consequence of fuel-air combustion within an internal combustion engine is the generation of noise (i.e., unwanted sound). A component of this noise is air intake noise that travels through the engine intake manifold and radiates from the air induction opening. Air intake noise varies in amplitude across a wide frequency spectrum depending upon the operational characteristics of the particular internal combustion engine. To the extent that the air intake noise is audible to passengers within the vehicle, it is undesirable.
Air intake noise can be reduced by employing a small diameter air inlet port within the air intake system. While this arrangement works well at low engine speed (i.e., low revolutions per minute (RPM)), the engine will not be supplied with sufficient air at high engine speed (i.e., high RPM). Conversely, a large diameter air inlet will provide sufficient air at both high and low engine speed, however, such an arrangement leads to increased air intake noise as well as being susceptible to water and snow intrusion due to the large air inlet opening. Conventionally, a snorkel and resonator arrangement (e.g., a Helmholtz resonator) is employed to reduce air intake noise, however, snorkel noise remains a challenge since conventional air intake systems strike a compromise to support both high and low engine speed, and cannot adapt to changing air requirements of an internal combustion engine.
Accordingly, it is desirable to provide an air intake system for an internal combustion engine that can adapt to engine air requirements. Also, it is desirable to provide a variable air intake system that offers protection against water and snow intrusion for the protection of the engine. Additionally, other desirable features and characteristics of the present invention will become apparent from the subsequent description taken in conjunction with the accompanying drawings and the foregoing technical field and background.